Microsurgical considerations of the anterior spinal and the anterior-ventral spinal arteries

Summary Background. There are few data describing the microanatomy of the anterior-ventral spinal (AVSA) and anterior spinal arteries (ASA) and discussing their clinical and surgical implications. We describe the anatomical features of this arterial complex, and highlight their use when planning and performing surgical approaches to lesions involving the ventral aspect of the medulla and the foramen magnum. Method. The microsurgical anatomy and branching pattern of the AVSA and the ASA from fifty human cadaver brain stems is described using a surgical microscope. Results. We found one anterior-ventral spinal artery at each side in 30 of the brain stems (60%). The ASA was a direct branch emerging from the left vertebral artery (VA) in 15 (30%), from the right VA in 4 (8%), and from the basilar artery (BA) in one brain stem (2%). The previously described as “typical pattern” of the junction of the AVS arteries from both sides, was observed only in 9 brain stems (18%). The anterior communicating spinal artery (ACoSA) was observed in 15 brain stems (30%). Also multiple ACoS arteries were described in one brain stem. Both, the AVSA and the ASA were observed to send long circumferential branches that supplied irrigation to the olive in 42 (84%) brain stems. Conclusions. This anatomical study gives important information for a better understanding of the clinical picture of ischemic lesions of the brain stem, such as the medial medullary syndrome, and highlights the remarkable role of the AVSA and ASA as anatomical landmarks during the surgical approaches to lesions involving the ventral aspect of the medulla and the foramen magnum.